C # DBHelper Class

Class DBHelper {//public static string connstr = "server=.;        database=superktv;uid=sa;pwd=123456 "; public static string connstr = "server=.;        database=dormitory;uid=sa;pwd=123456 ";        Database link object private static SqlConnection Conn = null;                Initialize database link private static void Initconnection () {//If the connection object does not exist, create a connection if (Conn = = null)            Conn = new SqlConnection (CONNSTR);            If the connection object is closed, open the connection if (conn.state = = connectionstate.closed) Conn.Open ();                If the connection is interrupted, restart the connection if (conn.state = = Connectionstate.broken) {conn.close ();            Conn.Open (); }}//query, get DataReader public static SqlDataReader Getdatareader (string sqlstr) {in            Itconnection ();            SqlCommand cmd = new SqlCommand (sqlstr, Conn); commandbehavior.closeconnection command behavior: Automatically closes the occupied Connection object when the DataReader object is closed returnCmd.        ExecuteReader (commandbehavior.closeconnection);             }//Query, get DataTable public static DataTable Getdatatable (String sqlstr) {initconnection ();            DataTable table = new DataTable ();            SqlDataAdapter dap = new SqlDataAdapter (Sqlstr, Conn); Dap.            Fill (table);            Conn.close ();        return table;            }//query, get DataSet public static DataSet GetDataSet (String sqlstr) {initconnection ();            DataSet ds = new DataSet ();            SqlDataAdapter dap = new SqlDataAdapter (Sqlstr, Conn); Dap.            Fill (DS);            Conn.close ();        return DS;            }//Add change to delete public static bool ExecuteNonQuery (string sqlstr) {initconnection ();            SqlCommand cmd = new SqlCommand (sqlstr, Conn); int result = cmd.            ExecuteNonQuery ();            Conn.close ();        return result > 0; }//execute aggregate function public static oBject executescalar (String sqlstr) {initconnection ();            SqlCommand cmd = new SqlCommand (sqlstr, Conn); Object result = cmd.            ExecuteScalar ();            Conn.close ();        return result; }    }

C # DBHelper Class